 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.ui.internal.ide.handlers;

 import java.util.ArrayList ;
 import java.util.Iterator ;
 import java.util.List ;

 import org.eclipse.core.commands.ExecutionEvent;
 import org.eclipse.core.commands.ExecutionException;
 import org.eclipse.core.commands.IHandler;
 import org.eclipse.core.commands.IHandlerListener;
 import org.eclipse.core.resources.IContainer;
 import org.eclipse.core.resources.IFile;
 import org.eclipse.core.resources.IResource;
 import org.eclipse.core.resources.ResourcesPlugin;
 import org.eclipse.core.runtime.ListenerList;
 import org.eclipse.jface.action.Action;
 import org.eclipse.jface.action.IAction;
 import org.eclipse.jface.dialogs.IDialogConstants;
 import org.eclipse.jface.viewers.ISelection;
 import org.eclipse.swt.widgets.Shell;
 import org.eclipse.ui.IWorkbenchPage;
 import org.eclipse.ui.IWorkbenchWindow;
 import org.eclipse.ui.IWorkbenchWindowActionDelegate;
 import org.eclipse.ui.PartInitException;
 import org.eclipse.ui.PlatformUI;
 import org.eclipse.ui.ide.IDE;
 import org.eclipse.ui.internal.ide.IIDEHelpContextIds;
 import org.eclipse.ui.internal.ide.dialogs.OpenResourceDialog;

 /**
  * Implements the open resource action. Opens a dialog prompting for a file and
  * opens the selected file in an editor.
  *
  * @since 2.1
  */
 public final class OpenResourceHandler extends Action implements IHandler,
         IWorkbenchWindowActionDelegate {

     /**
      * The identifier of the parameter storing the file path.
      */
     private static final String PARAM_ID_FILE_PATH = "filePath"; //$NON-NLS-1$

     /**
      * A collection of objects listening to changes to this manager. This
      * collection is <code>null</code> if there are no listeners.
      */
     private transient ListenerList listenerList = null;

     /**
      * Creates a new instance of the class.
      */
     public OpenResourceHandler() {
         super();
         PlatformUI.getWorkbench().getHelpSystem().setHelp(this,
                 IIDEHelpContextIds.OPEN_WORKSPACE_FILE_ACTION);
     }

     public final void addHandlerListener(final IHandlerListener listener) {
         if (listenerList == null) {
             listenerList = new ListenerList(ListenerList.IDENTITY);
         }

         listenerList.add(listener);
     }

     public final void dispose() {
         listenerList = null;
     }

     public final Object execute(final ExecutionEvent event)
             throws ExecutionException {
         final List files = new ArrayList ();

         if (event.getParameter(PARAM_ID_FILE_PATH) == null) {
             // Prompt the user for the resource to open.
 Object [] result = queryFileResource();

             if (result != null) {
                 for (int i = 0; i < result.length; i++) {
                     if (result[i] instanceof IFile) {
                         files.add(result[i]);
                     }
                 }
             }

         } else {
             // Use the given parameter.
 final IResource resource = (IResource) event
                     .getObjectParameterForExecution(PARAM_ID_FILE_PATH);
             if (!(resource instanceof IFile)) {
                 throw new ExecutionException(
                         "filePath parameter must identify a file"); //$NON-NLS-1$
 }
             files.add(resource);
         }

         if (files.size() > 0) {

             final IWorkbenchWindow window = PlatformUI.getWorkbench()
                     .getActiveWorkbenchWindow();
             if (window == null) {
                 throw new ExecutionException("no active workbench window"); //$NON-NLS-1$
 }

             final IWorkbenchPage page = window.getActivePage();
             if (page == null) {
                 throw new ExecutionException("no active workbench page"); //$NON-NLS-1$
 }

             try {
                 for (Iterator it = files.iterator(); it.hasNext();) {
                     IDE.openEditor(page, (IFile) it.next(), true);
                 }
             } catch (final PartInitException e) {
                 throw new ExecutionException("error opening file in editor", e); //$NON-NLS-1$
 }
         }

         return null;
     }

     public final void init(final IWorkbenchWindow window) {
         // Do nothing.
 }

     /**
      * Query the user for the resources that should be opened
      *
      * @return the resource that should be opened.
      */
     private final Object [] queryFileResource() {
         final IWorkbenchWindow window = PlatformUI.getWorkbench()
                 .getActiveWorkbenchWindow();
         if (window == null) {
             return null;
         }
         final Shell parent = window.getShell();
         final IContainer input = ResourcesPlugin.getWorkspace().getRoot();

         final OpenResourceDialog dialog = new OpenResourceDialog(parent, input,
                 IResource.FILE);
         final int resultCode = dialog.open();
         if (resultCode != IDialogConstants.OK_ID) {
             return null;
         }

         final Object [] result = dialog.getResult();

         return result;
     }

     public final void removeHandlerListener(final IHandlerListener listener) {
         if (listenerList != null) {
             listenerList.remove(listener);

             if (listenerList.isEmpty()) {
                 listenerList = null;
             }
         }
     }

     public final void run(final IAction action) {
         try {
             execute(new ExecutionEvent());
         } catch (final ExecutionException e) {
             // TODO Do something meaningful and poignant.
 }
     }

     public final void selectionChanged(final IAction action,
             final ISelection selection) {
         // Do nothing.
 }
 }

